Heart valves, such as the mitral valve, tricuspid, aortic and pulmonic valves, are sometimes damaged by disease or by aging, which can interfere with the proper functioning of the valve. Heart valve problems generally take one of two forms: stenosis, in which a valve does not open completely such that the opening is too small, resulting in restricted blood flow; or insufficiency, in which a valve does not close completely, permitting blood to leak backward across a valve that should be closed. The most common form of heart valve disease is aortic stenosis where the aortic valve leaflets become calcified and stiff, reducing the functioning valve area. The underlying disease state may be congenital or acquired. Valve replacement may be required in severe cases to restore cardiac function. The native aortic valve is removed and replaced with a prosthetic valve, or a prosthetic valve is placed within the native valve. The valve replacement may be a mechanical or biological valve prosthesis.
Another treatment approach for aortic stenosis is aortic valvuloplasty, also referred to as balloon valvotomy. During valvuloplasty, a dilating balloon is inflated to help crack the calcification on the valve leaflets allowing them to move more freely. This may be a stand-alone treatment giving a patient improved valve function for 6 to 12 months, or it may be a conjunctive treatment, preparing the valve before a valve implant. As shown in FIG. 1, aortic valvuloplasty includes positioning an unexpanded balloon 108 of a balloon catheter 106 across the aortic valve 100 so that balloon 108 spans valve 100 with one end of balloon 108 being located in the aorta 102 and the other end of balloon 108 being located in the left ventricle 104. Once thus positioned, balloon 108 is inflated to dilate the patient's aortic valve as shown in FIG. 2, thereby relieving the stenosis. Since blood flow through the valve is often blocked during the procedure, correct placement of the balloon may be facilitated by accelerating the heart rate with an external pacemaker to reduce cardiac output and ventricular pressure.
The present disclosure is directed to a balloon for use in valvuloplasty that allows for perfusion during the procedure and that may be more readily secured and centered at the treatment site.